Method for coating particles with inert powder



Nov. 24, 19 5. 1,562,821

L. A. BUNDS unmonron comma PARTICLES WITH mm POWDER F'i1 ed Ap ri1v14;1925' I N VEN TOR. M

A TTORNEYS Patented Nov. 24, 1925. I

UNITED STATES p r 1,562,821 PATENT OFFICE LESTER A. BUNDS, OI SANTACLARA, CALIFORNIA, ASSIGNOR TO SAN JOSE SPRAY' MFG. ('10., OF SAN JOSE,CALIFORNIA, A CORPORATION OF CALIFORNIA.

METHOD FOR COATINCTARTICLES WITH INERT POWDER...

Application filed April 14, 1925. Serial No. 23,026.

lowing is a specification.

My invention is particularly adapted .to the production of'a readilysolub le copper sulphate and is a further improvement on the process setforth in my co-pending application Serial No. 681,086, filed December17, 1922150 which reference is-here' made.

Copper sulphate is extensively used in the arts and in the preparationof insecticides, sprays, and the like and unless especially prepared,is'extremely difiicul'tto dissolve. The blue stone or copper sulphate ofcommerce is a crystallineproduct and the crys tals because of water ofcrystallization or deliquescence adhere together and agglomerate into asolid mass wliich must dissolve from the outside in, which is anextremely slow procedure even with constant stirring.

Ihave found that by grinding copper sulphate and coating the particlesthereof with a more finely ground inert powder, the particles of coppersulphate are held apart and agglomeration is prevented, and in suchcondition the prepared copper sulphate readily dissolves in water. Ihave found tale to be very effective as such an inert powder.

It is the 'ob'ect of my present invention, as herein set orth to prepareand coat the copper sulphate particles while they are in a driedcondition. by the employment of suitable process steps and apparatus andthe employment of heat.

These objects I attain by grinding the copper sulphate, preferably inthe presence of a more finely ground inert powder and then separatingand intermixing the copper.

5 the current of air carrying the particles is sulphate particles andthe, inert powder particles in a current of heated-air', whereby thecopper sulphate is dried and'brought' into intimate contact witlithefiner inert particles so that each unit particle ofco per sulphate iscovered byathe inert particleswhich adhere thereto during the dryingstep.

After the mass in finely divided condition, has passed, with thecurrentof hot air, through suitable conveying means it is preferablydelivered into a separator wherein Whirled about, during whichthecentrifugal force separates. the copper sulphate coated particles inthe outer portions of the separator and any superfluous inert powder isdrawn oif through a central opening in the separator.

By referring to the accompanying draw ing my invention will be madeclear Wherein is-shown partly in section and partly in elevation a sideview of; the apparatus adapted to employ my invention.

Referringto the drawing; The numeral 1 indicates a conyentional grindingapparatus into which the-copper sulphate to be ground is introduced asindicated by the arrow 2. I

While I prefer to introduce the inert powder together with the coppersulphate, this is not essential and it may be introduced after thecopper sulphate is ground as through? any suitable inlet for example, inthe direction of the arrow 3 into the fan 4. The fan is driven from theshaft 5 and operated from the motor 6which prefer.-v

8 through the pipe 9 to the suction sideof the fan 4.

i The current of air established by the fan picks up the groundparticles and with the more finelyground inert powder either introducedat 2 or through the suitable-open ing on the suction side of'the pump asindicated by the arrow 3, and conveys the same through the pipe 10. IDuring the travel of the particles through the pipe 10 the finerground-particles of inert matter adhere. all over the surfaces of thecopper sulphate particles, so that when the. mixture is delivered intothe centrifugal separator 11 the coated particles. are whirled to theoutside by centrifugal force and follow through the funnel 12, deliverypipe 13, and into the collecting hopper 14 as a finished product.

Any superfluous inert powder Which doesnot adhere to the copper sulphateparticles is drawn off through center connection 25 as by anyconventional suction means acting through the pipe 26. Y

I have found that the application of heat to the ground copper sulphateis advahtageous in removing any superfluous. moisture and a portion ofthe water oi crystallization and this drying I accomplish by providingan air inlet at 15 in a connecting pipe 16 which passes'into'the fanconnection 7 either through the box 8 or separately therefrom.

The pipe 16 is heated in the compartment. 17 as by the oil flame 18supplied from the tank 19-and injector apparatus 20, the product -ofcombustion passing up through the chimney 21. a V

In practice the-pipe 16 is maintained at a red hotor high temperatureand thus the air passing in at. 15 ishighly heated when it comes incontact with the ground copper sulphate particles and abstracts therequisite superfluous moisture therefrom and during the travel from thesump 8 into the separator 11.

Duringthis drying step the inert particles are seized and held on thecopper sulphate part-iclesas atenacious surface coating thus hOllIllIlfLevery copper sulphate particle separated fromits neighbors in theresulting mass that falls in the hopper 14; suit able for packingtransportation and,indefi-' nite handling.

Iclaim: I 1. The method of preparing a readily soluble copper sulphatewhich consists of grinding the copper sulphate'with a more finely groundinert substance and then conveying the mixture in a current of hot airwhereby a portion of the contained moisture is dried from thecoppersulphate with-the inert particles adhering to the copper sul- Themethod of preparing a crystalline salt which consists of conveyin theground salt in acurrent of hot air whi e intermixed with an inert andmore finelyground powder, whereby the evaporation from the saltparticles leaves'a salt'residue on the particles in which the inert.particles are held.

LESTER A. BUNDS.

